Laura Biagiotti, an Italian fashion designer who conquered global markets with her soft, loose women's clothes and luxurious knits which won her the nickname "Queen of Cashmere", has died aged 73.

Biagiotti suffered a heart attack at her estate outside Rome on Wednesday evening. Doctors were able to resuscitate her but by then serious brain damage had occurred.

Her daughter, Lavinia Biagiotti, announced her mother's death on Friday on Twitter, conveying the news with a Biblical passage: "In the house of my father there are many places. If not, I would have told you. I am going to prepare a place for you."

Biagiotti began designing women's clothes in the 1960s and by the 1980s was making her mark.

In 1988, she became the first Italian designer to put on a fashion show in China, presenting dresses and blouses in silk and cashmere. Several years later she was the first to have a show inside the Kremlin walls in Moscow.

She expanded into men's clothing as well, and created a plus-size women's line, Laura Piu, and the Biagiotti Junior line for children.

Her company also produced sunglasses and perfumes, including the popular "Roma" fragrance, named after Biagiotti's home city.

Born on August 4 1943, Biagiotti had planned to become an archaeologist but abandoned those plans to help her mother run a dressmaking business.

In those early years, she travelled frequently to the United States to learn business and technology. After collaborating with such famous fashion houses as Shubert and Capucci, she presented her own collection in Florence in 1972.

"Being a fashion designer is like taking vows. It becomes your religion for life," she told the Associated Press in 1987.

She was always deeply proud of her native Italy, and for years wore a cashmere shawl woven in the red, white and green colours of the nation's flag.

"I'm convinced that the true gold mine in our country is the 'Made in Italy' label," she said in 2011.

Biagiotti lived in a 14th century castle on a hilltop outside Rome that she had restored, and which was the headquarters for her business.

Her husband, Gianni Cigna, died of leukaemia in 1996.

She is survived by her daughter Lavinia, who had also been her fashion partner.